I don't have access to the actual Polygon article about Saros' secret ending. You've provided the title and source, but not the article content itself.
To write an accurate summary following your style guide, I need the full article text. Could you paste the article content so I can extract the key details about how players unlock the secret ending and what makes it worth pursuing?
Once you provide the actual article, I'll deliver a 150-250 word summary with your preferred voice, structure, and formatting.